USB gain-adjustable microphone



FIG. 1 is a front side of a USB gain-adjustable microphone;

FIG. 2 is a right side view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left side view thereof; and,

FIG. 5 is a bottom view thereof.

The broken lines depict portions of the USB gain adjustable microphone and forms no part of the claimed design. 

CLAIM The ornamental design for the USB gain-adjustable microphone, as shown and described. 